Nonsynchronous conveyor system

ABSTRACT

The machine has vertical tracks forming one or more continuous loops with or without transfer mechanism therebetween which permits sub-assemblies on fixture mounted pallets on carriers of one loop to be progressively worked upon at stations and transferred to sub-assemblies on pallets of carriers on one or more other loops to continue the assembly operations until the product is completed. The carriers are stopped in a collecting area ahead of the stations and are positively advanced out of and into the stations where the pallet is accurately located and clamped. The work performed at the station is checked to make certain a correct operation was performed and if an indicating flag shows that it was not, the carrier is passed through the stations thereahead. If the station is defective and continues to perform its operation badly, a carrier stop mechanism may be attached to the track ahead of the station to have the operation performed on the workpiece manually until the defect in the station has been corrected.

Shepard et al.

nited States Patent 119i [451 Jan. 15,1974

[ NONSYNCHRONOUS CONVEYOR SYSTEM [73] Assignee: Standard Tool & Manufacturing Co., Lyndh-urst, NJ.

22 Filed: Jul 19,1972

[21] Appl. No.: 273,321

Primary ExaminerThomas H. Eager A!torney.l. King Harness et al.

[ 5 7 ABSTRACT The machine has vertical tracks forming one or more continuous loops with or without transfer mechanism therebetween which permits sub-assemblies on fixture mounted pallets on carriers of one loop to be progressively worked upon at stations and transferred to subassemblies on pallets of carriers on one or more other loops to continue the assembly operations until the product is completed. The carriers are stopped in a collecting area ahead of the stations and are positively advanced out of and into the stations where the pallet is accurately located and clamped. The work performed at the station is checked to make certain a correct operation was performed and if an indicating flag shows that it was 'not, the carrier is passed through the stations thereahead. lf the station is defective and continues to perform its operation badly, a carrier stop mechanism may be attached to the track ahead of the station to have the operation performed on the workpiece manually until the defect in the station has been corrected.

28 Claims, 33 Drawing Figures PATENIEDJMI 1 5 m4 SHEET 02 0F 17 i 0 w w. w M Infl w WW a h W W WW 2 1 7 1|. m 4 1 l L it m AV E 1? saw user 17 Pmimwmwsmm SHEET 05 0F 17 sxrasgosl PATENTEDJAH 15 m4 SHEET 07UF17 BL'TBBLBEBI PATENIED JAN 15 I974 SIEET DBDF 1T PATENTEUJMI 151914 saw 090? 17 PATENTEUJAN 15 m4 SHEET IOUF 17 PATENTEUJAN 15 1914 3.785331 sum 12 0F 17 3785mm saw 150$ 17 PATENTEU JAN 15 I974 1 NONSYNCIIIRONOUS CONVEYOR SYSTEM BACKGROUND OF THE INVENTION Reference may be had to U.S. Pat. No. 3,646,656, issued Mar. 7, 1972 to Z. E. Zilahy et al. for Machine Having Overhang Supports for Pallets and assigned to the assignee of the present invention and also U.S. Pat. No. 2,856,054 and Reissue U.S. Pat. No. 25,886 to show machines having free carriers driven by a chain.

RELATED APPLICATION Reference may be had to the application of A. L. Dato et al., Ser. No. 128,305, filed Mar. 26, 1971 for Control Mechanism For Advancing and Locating Pallets" for a disclosure of a shuttle control for advancing a pallet into a station.

SUMMARY OF THE INVENTION The invention pertains to the control for carriers which are mounted on a vertically disposed track in a closed loop. The carriers have a vertically disposed body portion with rollers thereon which guide it along the track. The carriers are provided with an overhanging pallet supporting ledge on which the pallet rests as it is advanced between the stations. The pallets may be employed for supporting workpieces which are moved into a station to have a machine operation performed thereon or to have an assembly operation take place depending on whether the machine is to perform machining or assemblying operations or both. The system illustrated shows two loop portions and is constructed for assembly operations, the first loop portion assembles the parts for one sub-assembly, the other loop portion assembles the parts of another subassembly with a transfer device between the loop portions which moves the sub-assemblies together and completes the product therefrom.

In the machine illustrated, one loop portion approximately 75 carriers thereon while the other loop portion has approximately 107 carriers thereon. Substantially all of the assembly operations at a station can be performed in a predetermined time which may be five seconds. Several other operations may require more time, say approximately eight seconds. Two stations are provided at this point of the assembly so that eight-second operations can be performed at the two stations while two normal operations will be performed in seconds of time. To positively advance the carriers into and from the stations a shuttle mechanism is provided which first applies a brake to stop the carrier in the collecting area ahead of a station without shock or noise and to release it to have it advanced a very short distance by the chain to a positive stop.

Stop elements and fingers are mounted on an angularly shiftable longitudinally movable shuttle bar which permit the stop elements to be moved from, and the fingers to be moved between the wear plates at the bottom of adjacent carriers. The shuttle bar is then advanced to move the carriers and pallets from and into the station a distance of approximately 17 inches. The pallet is engaged and secured to accurately locate the workpiece thereon relative to the elements at the station which performs the work operation thereon. The advancement of the carrier into the station positively advances the preceeding carrier therefrom which is released by the foremost finger and stop element. When the fingers are moved from between the wear plates leaving the stop element therebetween the shuttle bar is returned to its retracted position ready to advance the next adjacent carrier retained in the collecting area ahead of the station.

A carrier stop mechanism may be attached at substantially any point along the track for stopping a carrier thereat. A valve operated element actuated by the hand, foot, timing element or the like raises a lever which intercepts the brake lever for stopping and releasing the carrier which is advancing along the track. This permits the manual performance of an operation near a station where a defective operation was performed. A flag system and reader checks the operation performed at each station and if found defective, no further operations will be performed thereon and the manual mechanism is employed ahead of the station until the operation performed at the station is corrected.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a machine having two palletized closed loops with a transfer mechanism therebetween which embodies features of the present invention;

FIG. 2 is a sectional view of a vertical track for a plurality of carriers having a pallet thereon with drive means for the carrier;

FIG. 3 is an enlarged broken plan view of the driving sprocket for the chain which advances the carriers on the track;

FIG. 4 is a sectional view of the structure illustrated in FIG. 3, taken on the line 44 thereof;

FIG. 5 is an end view of a station into which the carrier is advanced to have a work operation performed on the workpiece thereon;

FIG. 6 is a front view of a carrier with a brake thereon operated from a carrier ahead thereof;

FIG. 7 is a sectional view of the structure illustrated in FIG. 6, taken on the line 77 thereof;

FIG. 8 is a front view of a carrier stopping mechanism which may be applied to the carrier track at substantially any points therealong;

FIG. 9 is a broken end view of the structure illustrated in FIG. 8, as viewed from the righthand side thereof with a part in section;

FIG. 10 is a view of the structure illustrated in FIG. 8, as viewed from the lefthand side thereof;

FIG. 11 is a plan view of the shuttle mechanism located at a station into which a carrier is to be delivered;

FIG. 12 is a front view of the structure illustrated in FIG. 11;

FIG. 13 is an enlarged broken sectional view of the structure illustrated in FIG. 12, taken on the line 13-13 thereof;

FIG. 14 is a broken plan view of the mechanism for orienting and clamping a pallet at a work station;

FIG. 15 is an end view of the structure illustated in FIG. 14;

FIG. 16 is a view of a carrier at the time of leaving a station where the existence of a carrier thereat is checked;

FIG. 17 is a broken end view of the structure illustrated in FIG. 16, as viewed from the point 17 thereof;

FIG. 18 is a plan view of a pair of switch mechanisms actuated by the edge of a channel element attached to each carrier;

FIG. 19 is an end viewof the structure illustrated in FIG. 18;

FIG. 20 is an enlarged corner view of the structure illustrated in FIG. 18;

FIG. 21 is a sectional view of the structure illustrated in FIG. 20, taken on the line 21-21 thereof;

FIG. 22 is an enlarged broken view of the structure illustrated in FIG. 11, as viewed within the elipse 22 thereof;

FIG. 23 is a sectional view of the structure illustrated in FIG. 22, taken on the line 2323 thereof;

FIG. 24 is an enlarged end view of the structure illustrated in FIG. 12, as viewed from the line 24-24 thereof;

FIG. 25 is an end view of the drive mechanism for each station illustrated in FIG. 13 for advancing the shuttle bar and producing the rotary position thereof;

FIG.'26 is a sectional view of the shuttle bar rotated to a position for advancing carriers into and out of a station;

FIG. 27 is a view of structure illustrated in FIG. 26, with the shuttle bar rotated to a position for retaining the carriers in advanced position as th shuttle bar is retracted;

FIG. 28 is a view of the structure as illustrated in FIGS. 26 and 27 with the shuttle bar rotated to a position in which the carriers pass through a station without being stopped;

FIG. 29 is a view of structure, similar to that illustrated in FIG. 12, showing a different operating mechanism for the shuttle bar;

FIG. 30 is a view of structure, similar to that illustrated in FIGS. 25 to 28 for rotating the shuttle bar when the mechanism of FIG. 29 is employed at a station;

FIG. 31 is a broken enlarged view with parts in section of the structure illustrated in FIG. 14 with the flags, flag setters and flag readers in aligned relation;

FIG. 32 is a side view of the structure illustrated in FIG. 31 as viewed from the point 32 thereof, and

FIG. 33 is an end view of the structure illustrated in FIG. 31, with parts in section.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, a comprehensive palletized machine is illustrated having a first branch loop 31 for progressively operating on a workpiece which is to be assembled with an element operated on in a second branch loop 32. To be specific, one element of a product to be assembled has parts assembled thereon in the branch loop 31 of the machine and the other element of the product is assembled therewith and further worked upon to complete the product in the branch loop 32. The one element is transferred from the branch loop 31 to the other element in the branch loop 32 by a transfer station 33 located therebetween. It is to be understood that machining or assembling operations could be performed at a station separately or a combination of both could be performed. Vertical track systems 35, forming the two branch loops 31 and 32, have carriers 36 supported on the outer face thereof for advancement therealong. An elongated pallet 37 is mounted on each carrier which is advanced from station to station where the assembly operations are performed seriatim thereon. In the device herein illustrated, each pallet supports a pair of elements 38 or 39 so that the pair can be operated upon simultaneously in each of the stations.

As illustrated in FIG. 2, the track has an inner plate 41 of predetermined length, the ends of which are attached to L-shaped supporting legs 40. The plates 41 support a top rail strip 42, a brake shoe engaging strip 43 in the center and a chain supporting strip 44 at the bottom. A chain 45 is of conventional form having rollers 46 which are interconnected by top and bottom overlapping links 47. Each link at the top of the chain has a wear plate 48 secured thereto which engages a wear plate 49 at the bottom of a carrier 36. The chain supporting strip 44 has wear strips 50 therealong of high molecular weight polyethylene which has high impact, shock and wear resistance. the wear strips are known under the name Pactene and are procurable from Schmidt Industries, 133 Court Street, Post Office Box A-995, New Bedford, Massachusetts 02741.

The carrier has rearwardly extending arms 52 and 53 on which rollers 54 are mounted in facing relation for running on tracks 55 on the top rail strip 42 and the brake shoe engaging strip 43. A vertically disposed roller 56 supported on a vertical body portion 57 of the carrier engages a face 58 of the top rail strip 42. The carrier extends outwardly at the top to form a horizontal platform 59 on which the pallet 37 is supported. The chain 45 is continuously driven at an arcuate corner 61 of the branch loops 31 and 32 by a driven sprocket 62 having a plurality of cam operated fingers 63 pivoted thereto which are held in operating position by a cam 64 and released from such position when dropping onto a dwell portion 65 thereof. It will be noted that the arcuate corner of the two closed loops 31 and 32 where the chain drive occurs has been enlarged to show the drive mechanism and the support therefor. The sprocket is illustrated, described and claimed in a copending application of Prescott V. Murphy Ser. No. 291,977, filed Sept. 25, 1972; for Chain Drive Having Pivoted Drive Teeth and assigned to the assignee of the present invention. The sprocket is driven at a predetermined speed from a motor through a gear reducing unit in the conventional manner. As the chain is driven, the wear plates 48 thereon have friction engagement with the wear plates 49 on the carriers 36 and advance the carriers along the track to a station where work is to be performed, such as the station 66 illustrated in FIG. 5. The carrier 36 is stopped in a holding area before it enters the station so that it can be positively advanced thereinto independently of the chain 45.

As illustrated in FIG. 5, a motor driven gear reduction unit 67 drives a reduction gear unit 68 to drive a shuttle mechanism 69 which advances the carriers into and out of the stations. The unit 67 also drives a gear reduction unit 70 which drives the work performing mechanism at the station. The carrier 36, after being advanced into the station, has its pallet 37 oriented longitudinally and transversely and raised and secured in predetermined position by a locking mechanism 71 operated by the station drive. The overhanging platform 59 of each carrier has rubber bushings 72 therein, as illustrated in FIG. 2, on which the pallet is supported. The platform 59 has a pair of pins 73 disposed on opposite corners in apertures 74 which contains an elastic sleeve 75. The elastic sleeve permits the degree of shifting of the pins in the plane of the platform necessary to accurately orient the pallet at a station. The forward edge of the carrier has a rubber bumper 76 which is 

1. In a palletized machine, a track, a chain supported by said track having wear plates thereon, carriers on said track having a wear plate in engagement with the wear plates of said chain for advancing the carriers along the track as the chain moves thereon, brake means on said carriers, a brake strip on said track engageable by said brake means, and means on said carrier for moving said brake means against said brake strip when actuated for stopping said carrier and for raising its wear plate from the wear plates of the chain to eliminate wear therebetween.
 2. In a palletized machine as recited in claim 1, wherein said brake means is actuated by a lever pivoted at the forward end of said carrier.
 3. In a palletized machine as recited in claim 2, wherein an element on the rear of each carrier is in position to operate said brake lever when one carrier approaches a carrier thereahead.
 4. In a palletized machine as recited in claim 3, wherein a pallet is mounted on each said carrier, and stations located along said track where operations are performed on workpieces supported on said pallets.
 5. In a palletized machine as recited in claim 4, wherein a lever is mounted ahead of at least some of said stations, and means for moving said levers into and out of the path of the advancing brake lever of a carrier for stopping said carrier in an accumulating area ahead of said station.
 6. In a palletized machine as recited in claim 1, wherein a shuttle bar is mounted at each said station, means for advancing and retracting said shuttle bar, and a stop element movable between the wear plates of adjacent carriers at the station and ahead thereof for retaining the carriers against advancement by said chain after the brake lever is released.
 7. In a palletized machine as recited in claim 6, wherein fingers on said shuttle bar are disposed adjacent to said stop elements for movement between the adjacent wear plates of the carriers as the stop elements are moved therefrom to permit the shuttle bar to advance the carriers into and from the station.
 8. In a palletized machine as recited in claim 7, wherein means are provided for detecting the presence of a carrier within the station and the absence of a carrier therein.
 9. In a palletized machine as recited in claim 7, wherein a plurality of carriers are stopped ahead of the station and engaged by said stop fingers to be advanced simultaneously into a plurality of adjacent stations as the plurality of carriers therein are positively advanced therefrom.
 10. In a palletized machine as recited in claim 6, wherein means are provided for moving the lever ahead of the station out of engagement with the brake lever to lower the wear plate of the carrier onto the wear plate of the chain which advances the carrier a very short distance into engagement with said stop element which is under the control of the shuttle bar.
 11. In a palletized machine as recited in claim 7, wherein means are provided for moving the fingers and stop elements out of the path of engagement with the wear plates of the carriers to permiT the carriers to continue through the station without being stopped.
 12. In a palletized machine as recited in claim 1, wherein said carrier supporting track is vertically disposed and provided with a channel in which said chain is advanced, and plastic elements on each side of said channel on which the chain wear plates are supported and advanced.
 13. In a palletized machine as recited in claim 12, wherein pallets are supported on top of the carriers, and pins extend upwardly from said carriers through fitted holes in said pallet for retaining the pallet against shifting relative thereto.
 14. In a palletized machine as recited in claim 13, wherein said pins are mounted in an elastomeric material to permit them to shift with the pallet when the latter is accurately located at a station.
 15. In a palletized machine as recited in claim 14, wherein elastomeric material on the top of the carrier supports the pallet out of engagement with the metal thereof.
 16. In a palletized machine as recited in claim 14, wherein the drive for operating the work performing elements at the station moves a spring pressed slide against one edge of the pallet to accurately locate the pallet and lock it in located position.
 17. In a palletized machine, a track, carriers on said track, a plurality of stations along said track, means for advancing carriers along said track into said stations, a pallet on said carrier for supporting a workpiece to be operated on in a station, a work performing indicator on said pallet and carrier, a reader for said indicator located at a holding area ahead of a station, means actuated at the station for performing a work operation on the workpiece on the pallet, and means for retaining a carrier in said holding area so that the indicator can be read.
 18. In a palletized machine as recited in claim 17, wherein said reading provides indications of ''''good'''' or ''''bad'''' operations performed at the station ahead of the one to which the carrier was advanced.
 19. In a palletized machine as recited in claim 18, wherein said work performing indicator is an axially shiftable rod and wherein said reader is a proximity switch which indicates the longitudinal position of the rod.
 20. In a palletized machine as recited in claim 19, wherein means are provided between said proximity switch and stations which is engaged by one end of the rod as the carrier moves thereby for shifting said rod to ''''bad'''' operation position, and resetting means at the station for moving the rod to ''''good'''' position if a good operation has been performed.
 21. In a palletized machine as recited in claim 20, wherein said resetting means is an air cylinder, and a switch actuated at the prior station when a defective operation is performed thereat for preventing air to be supplied to the resetting air cylinder at the advanced station so that the longitudinal position of the rod showing a ''''bad'''' operation is retained.
 22. In a palletized machine, a track, carriers on said track, a plurality of stations along said track, means for advancing carriers along said track into said stations, a pallet on said carrier for supporting a workpiece to be operated on in a station, drive means for the mechanism which performs work at the station, means locating and clamping the pallet at the station, and means driven by said drive means for operating said locating and clamping means.
 23. In a palletized machine, a track, carriers on said track, a plurality of stations along said track, means for advancing carriers along said track into said stations, a pallet on said carrier for supporting a workpiece to be operated on in a station, an indicating means for indicating whether a ''''good'''' or ''''bad'''' operation was performed at the station, and means actuated when the indicator is ''''bad'''' for passing carriers through the station without any work being performed thereon.
 24. In a palletized machine, as recited in claim 23, wherein an attachable carrier stop mechanism is securable to said track ahead of said station in position to stop carriers advanced on said track to have the operation indicated ''''bad'''' at the station performed manually at the attached stop mechanism until the defect at the station has been repaired.
 25. In a palletized machine, a pair of loops formed by tracks, carriers on said tracks, a plurality of stations along said tracks, means for advancing carriers along said track into said stations, a pallet on said carrier for supporting a workpiece to be operated on in a station, means for performing assembly operations on workpieces in each loop as the carriers are passed from one station to another, and a transfer mechanism located between said pairs of loops for transferring an element from one loop which had the operations completed thereon and assembled in an element in the other loop.
 26. In a palletized machine, a track, carriers on said track, a plurality of stations along said track, means for advancing carriers along said track into said stations, a pallet on said carrier for supporting a workpiece to be operated on in a station, drive means having a single revolution clutch, an overload clutch and a cam plate having a pair of cam tracks, means for releasing and engaging said single revolution clutch for advancing and retracting the shuttle bar, and means actuated by the track of said cam plate for rotating said shuttle bar to locate the finger and stop elements thereof relative to the carriers at each end of the reciprocating cycle of the shuttle bar.
 27. In a palletized machine, a track, carriers on said track, a plurality of stations along said track, means for advancing said carriers along said track, a pallet on said carriers for supporting a workpiece to be operated on in a station, shuttle means for advancing the carriers a predetermined distance into a station where the work operation requires a predetermined minimum time for the single station operation, a second shuttle means for simultaneously advancing two carriers into two stations where two times the predetermined time for the work operation will be had so that all of the workpieces on the carriers can be worked upon and advanced within the period of said predetermined time.
 28. In a palletized machine, a track, carriers on said track, a plurality of stations along said track, means for advancing said carriers along said track into said stations, a pallet on said carriers for supporting a workpiece to be operated on in a station, brake means on each said carrier disposed between the front and back face thereof, a first arm extending forwardly of the carrier between the front and back faces thereof to be operated by an element at the rear of a carrier located thereahead, a second arm extending outwardly from the front face of the carrier, and a lever located out of the path of advancement of the carrier and in the path of advancement of said second arm for producing the brake operation when engaged thereby. 